Container closure and lining composition



April 25, 1944. O'R 2,347,618

CONTAINER CLOSURE AND LINING COMPOSITION 1 Filed July 25, 1940 INVENTORKENNETH TATOR ATToRNEY.

Patented Apr. 25, 1944 CONTAINER CLOSURE AND LINING COMPOSITION KennethTater, Egypt, Mass, assignor to Dewey and Almy bridge, Mass. a

Chemical Company, North Camcorporation of Massachusetts Application July25, 1940, Serial No. 347,541 In Canada June 1'1, 1935 6 Claims.

This invention relates generally to the art of container closure andspecifically is directed to the production of a superior liningcompound. Among the objects of the invention are to provide a method ofincorporating substantial amounts of fibrous fillers in the compoundwithout at the same time unduly increasing its viscosity; to preventsubstantial hydration of the fibre; and to produce a fibre-reinforcedlinin compound.

These and other objects will become apparent from the specification andfromth e drawing in which the single figure represents a greatlyenlarged cross-section through a portion of a double seamed can body andend.

The present application is a continuation-inpartof my divisionalapplication, Serial No. 196,-

800, filed March'l8, 1938, which application contains subject matterdivided from my Patent No. 2,134,217, patented October 25, 1938. Mypatent contains claims covering the process of preparing water-resistantsealing gaskets on container closures and the resulting article ofmanufacture, while the claims of the present application are directed tothe novel water-resistant compound and the process of manufacturing. thesame.

It has been the previous experience that organic or mineral fibres (typesubstances are cellulose. and asbestos) cannot be added to awaterdispersed can-lining compound in substantial amounts because suchfibres hydrate readily and form sluggish viscous masses quite unsuitablefor can lining purposes. For example, a water slurry containing 8% ofdry fibre is too stifi for the purposes of this invention. Thecontrolling factor is, of course, the viscosity limits which arerigidlyset by the nature of the lining machinery and the configuration of thecan ends used.

If rubber and wood pulp or cotton fibres are worked on a rubber mill,the fibre is drawn into the rubber by the apparent process of wetting.

It is my belief that the rubber particles wet the individual cellulosicfibres and also that this wetting is preferential and persists in thepresence of water. In certain cases, notably with news ried in may equalthe weight of the rubber. In

the amount of dried fibre which can be car-- .tective colloid servescipitate rubber upon the fibres in the manner he.

has described. When dried, such coated fibres may be milled into arubber mass over a very wide range of proportions. If asbestos be used,I consider it advantageous but not strictly necessary to precoat thefibres with rubber latex and in such case I may utilize the process setforth by G. R. Tucker in U.'S. PatentsNos. 1,907,616 and 1,907,611.

I have discovered that such high fibre content mixtures can be dispersedunder certain conditions and that the coated (or rubber wetted) fibresdo not hydrate'in a comparable degree to untreated fibres in water.Without regard to the accuracy of my explanation .of this effect, I noteas a fact that I am able to produce a water dispersed lining compoundcontaining one part of fibre to one part of rubber solids and still havea viscosity which is suitable for lining machine requirements.

' I have also discovered that this efiect is not limited to rubber 'orits analogues but occurs generally whenever a substantiallynon-hydratable body is used. For example, excellent low viscositydispersions based on asphalt, parafiin and waxes may also be made.

It is widely believed that the dispersion of rubber in water is broughtabout by the repeated stretching of the rubber mass and the introductionof water between the rubber globules with each extension. It is alsostated that the proboth to carry in the water and to coat the rubberglobules to prevent their .re-coalescence. Whether this be true or not,the

fact remains that rubber to disperse well in a mixer must originallypossess some nerve. The mixture of one part fibre, one part rubber is,however, soft and crumbly and cannot be dispersed with the cheap andcommonly used dispersing agents such as kaolin and bentonite. They areunctuous and slippery. Soap dispersing agents also fail; property ofnerve need not reside in the rubher, but may be introduced as anattribute of the colloid. Substances such as casein, glue, gelatin,karaya, sea moss and the algins attach themselves so firmly to therubber and have such high elfcohesion that the pulling and stretchingofthe rubber necessary to produce a dispersion can be brought about;

The seal produced But, I have found that the.

by my compound is i1lus-' trated in the figure, a sectional view througha into a Baker-Perkins mixer and worked with 100- parts of casein mixedwith 150 parts of ammonia water (28%NH3). Additional water to the amountof 1500 parts is run into the mixer bit by bit as the process continues.The mixing is continued until the rubber is "thoroughly dispersed and asmooth paste is formed. Compounding ingredients may -be added to themass which may be viscosity or plasticity factors such as are disclosedin the patent to Dewey and Crocker, No. 1,765,134, or they may bevulcanizing agents. The addition of such factors has no efiect on thegeneral nature of the dispersion I produce.

In the same general manner, I am able to produce dispersions of wool,cattle hair, shoddy, or asbestos. As I have previously stated, myinvention is not limited to coating the fibres with rubber, or likesubstances alone, but asphalt, Waxes and parafiin may be used in themanner specified. In the case of wax the addition of an ethanol-aminemay be found helpfuland in all cases a disinfectant or preservative aidswhen the dispersions are to be stored.

The above formula is, accordingly, given for illustrative purposes onlyand no limitation is intended by reason of the materials given or theproportions stated therein. Those familiar with the art will recognizethat the proportion of fibre which can be added may vary through widelimis employed to indicate-a system involving a continuous phase and atleast one dispersed phase wherein the continuous phase comprises water,and the discontinuous or dispersed phase comprises solid particlesfreely suspended in the continuous phase. Such a systemis distinguishedfrom a mere mixture by the fact that the dispersed phase is stable anddoes not have any substantial tendency to settle out.

I claim:

1. The method of making a stable aqueous dispersion which comprisesmilling cellulosic fibres into rubber to coat the fibres with rubber andthen intensively working the resulting mass with water and a dispersingagent selected from the class consisting of casein, glue, gelatin,karaya, sea moss and algin to disperse the mass as a stable dispersephase in water.

2. That method of producing a water dispersion containing rubber and asubstantial proportion of fibre both in the disperse phase whichincludes the separate steps of coating said fibre by coagulating latexthereon, incorporating said coated fibres in an additional quantity ofrubber by milling and then forming a dispersionby working the milledbatch in the presence of water and a material selected from the classconsisting of casein, glue, gelatin, karaya, sea moss and the algins.

3. The method of making a stable aqueous dispersion which comprisesmilling cellulosic fibres into a waterrepellent substance selected fromthe class consisting of rubber, asphalt, paraflin, and waxes to coat thefibres with said substance and then intensively working the resultingmass with water and a material selected from the class consisting ofcasein, glue, gelatin, karaya, sea moss and algin to disperse the massas a stable disperse phase in water.

4. A stable aqueous dispersion, being the product of the process ofclaim 1.

a 5 A stable aqueous dispersion, being the prodnot of the process ofclaim 2.

6. A stable aqueous dispersion, being the product of the process ofclaim 3.

. KENNETH TATOR.

